Nearly 120 years after the signing of the Emancipation Proclamation, the federal government is trying a slavery case in North Carolina.

In a case of potentially national significance to thousands of migrant workers and the farmers who depend on their labor, four men are charged with conspiracy to hold at least eight men in involuntary servitude in a migrant camp at Rainbow Farms, less than an hour's drive east of Raleigh.

The trial is to open today in district court here.

A six-count federal grand jury indictment issued in October alleges that migrant crew leader Dennis Warren, his brother Richard, and two other men lured workers from New York, Atlanta and Baltimore to Rainbow Farms with promises of good wages, liquor and drugs, then threatened to shoot or beat them if they tried to leave.

The Warrens' co-defendants, John Lester Harris and Halsey Norwood, also are charged with abducting a pedestrian from a Raleigh street and taking him to a farm near the Tar River.

If convicted, the men could face life imprisonment, because it is charged that one of the workers died of heat exhaustion after Dennis Warren refused to allow him to stop gathering sweet potatoes even though the man was spitting up blood.

The defendants deny the charges.

The Warrens were arrested Sept. 25, four days after a farm worker who said he had escaped from Rainbow Farms came to the FBI office in Raleigh. An FBI spokesman said agents who raided the camp twice in late September freed 13 men ranging in age from their 20s to the 60s. Most of the men were black, as are the Warrens.

Stephen Nagler, executive director of Migrant Legal Action, a national organization headquartered in Washington, D.C., estimated that from 50,000 to 100,000 farm workers in the United States may be held in forced service, many by crew leaders, the independent labor contractors who supply manpower to harvest farmers' crops.

"We're talking about a fairly comprehensive system of exploitation and abuse," Nagler said. "Even 100 prosecutions a year would only succeed in knocking the tip off the iceberg."

But the North Carolina case, he said, could be "an exemplary kind of case, a case that says to people that engage in practices of this sort that they may in fact be prosecuted."

Through November, the Justice Department was investigating 25 slavery cases in 11 states, said Richard W. Roberts, a civil rights division attorney who a year ago became the department's first coordinator of involuntary servitude complaints.

Since 1980, 16 persons have been indicted on slavery and related charges.

Three of the government's four convictions during that period came in United States vs. Booker. That case also involved charges of crew leaders exploiting migrants in eastern North Carolina, where the majority of the state's estimated 40,000 to 50,000 migrants pick cucumbers, peppers, sweet potatoes, tobacco, melons and other crops.

The Booker case bolstered prosecutors' contentions that workers could be enslaved even within sight of an obvious route to freedom.

"The availability of escape, as the history of slavery has shown, or even a situation where the discipline of terror is not constantly enforced, does not preclude a finding that persons are held as slaves," wrote Judge Harrison L. Winter of the 4th U.S. Circuit Court of Appeals in denying Tony Booker's appeal in July, 1980.

According to Justice Department documents filed in the Warren case, conditions for such subjugation existed at Rainbow Farms. "Many of the victims were told that they would be beaten or 'manhandled' if they attempted to do so," the documents allege.

"Further, some workers who attempted to leave the camps were forcibly returned . . . some of the defendants patrolled the camp or the fields carrying black rubber hoses. On occasion workers were hit with potato buckets."

Attorney L. Lamar Armstrong, who represents Dennis Warren, 19, and his brother Richard, 22, refused comment. Armstrong is a partner in the law firm that defended Booker.

But documents filed in district court indicate the defense will attempt to refute charges "that a fear pervaded the migrant camp to the extent that the wills of reasonable men . . . would be overborne."

Defense attorneys also are expected to challenge the character and, therefore, the credibility of the migrant workers upon whose testimony the goverment's case largely rests.

Attorneys, health workers and others familiar with migrant conditions in North Carolina say violence against and among the workers is common, and many of the migrant camps are patrolled at night by guard dogs.

In addition to securing work for the migrants, the crew leaders arrange for their housing, frequently in crudely appointed camps, and customarily deduct for food and lodging from workers' pay. Federal labor officials claim that crew leaders frequently underestimate the pay due workers and overcharge them for goods and services.

But Martin Boone, an Xaverian brother who has worked with farm workers in Sampson County, N.C., since 1979, says crew leaders, like the migrants they control, are victims of a system designed to benefit growers by getting crops picked with a minimum of delay and cost.

"People say around here, 'We used to own our slaves. Now we rent them,' " Boone said. "How do these conditions exist? To a large extent, the economy of the state depends on this."